In recent years, packet-switched data communication has become more commonplace. One of the newer arenas in which packet-switched technology has been applied is in connection with input/output (I/O) devices. A well-known example of packet-switched I/O technology is an InfiniBand® network (InfiniBand® is a registered trademark of System I/O, Inc.). The InfiniBand® specification defines a protocol by which a serial, full duplex, packet-switched data I/O communications network is established. The packet-switched nature of the network allows for more flexible topologies than a traditional bus design. Switches in the network interconnect multiple links by passing data packets between various ports. The network may also be broken down into “subnets,” which are connected to one another by routers. The subnets provide the network with a certain modularity not unlike “local” and “long distance” telephone services.
Communications between two points on an InfiniBand® network (sometimes referred to as a switch “fabric”) requires communications devices at each of the points. A general-purpose computer may be connected to the fabric with a “host channel adapter,” which is an intelligent interface that makes use of a direct connection to the computer memory to perform complex transfer operations. A “target channel adapter” is also a smart device, but is configured to work with an I/O device being accessed, such as a disk array. The target channel adapter does not need to be connected to a general-purpose computer.